You can't base a card's effect completely on its name. Just because the card is called explosion, doesn't mean it will "ignite" the gas. Think about a spell like fire lance. Just because it has the world lance or fire in it, doesn't mean that a creature will bleed (by the lance) or suffer excess burn damage (from the fire) if it doesn't die from the spell. Names are just important in identifying cards and creating an atmosphere and a game culture, but card mechanics are designed a certain way, and they precede the name of a card usually. I get what you are saying, and i know my analogy is completely ridiculous, but just because a card is called explosion, it doesn't mean it will ignite the gas (the link between explode and ignite isn't completely straightforward to begin with)
